From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 12D6EC54EAA for ; Mon, 30 Jan 2023 07:50:36 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pMOvN-0007wZ-RF; Mon, 30 Jan 2023 02:49:57 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1pMOvM-0007wR-GT for qemu-devel@nongnu.org; Mon, 30 Jan 2023 02:49:56 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1pMOvK-0007RM-Jj for qemu-devel@nongnu.org; Mon, 30 Jan 2023 02:49:56 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1675064993; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=KhrtKKpbeT/n7V/A+eL/e0X79p/knmlV6qLX0UYvqBs=; b=CiSgdWlqCfnsw9kHwjA64tJu53/eq85hBgknViqKkTk0LW+dUgnbAz5RRJ4lNyeCusQBWq TDlSUHL9OIW4c88I4rgpV39A/BHBH/0dFGBYA1BX7UA0Gt4pft5rUX6S5CEoak36YD6qGI L+1VzOzBzyi0pa9xA7ggsAAPDbaqgUw= Received: from mail-oi1-f199.google.com (mail-oi1-f199.google.com [209.85.167.199]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_128_GCM_SHA256) id us-mta-362-_o_GA1dGN062iLQs5S1Awg-1; Mon, 30 Jan 2023 02:49:48 -0500 X-MC-Unique: _o_GA1dGN062iLQs5S1Awg-1 Received: by mail-oi1-f199.google.com with SMTP id bo8-20020a056808228800b00377f0a70cf7so3489075oib.22 for ; Sun, 29 Jan 2023 23:49:48 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=KhrtKKpbeT/n7V/A+eL/e0X79p/knmlV6qLX0UYvqBs=; b=uWDz5+p1sv2Kg/XjqpblCOgA4lfSn06uHIP7iRnSO+hYkK8KSPkse0SmYz/BxNwi/I 5tJp/TbsIEGb4jJAFtHb7bkhnYgx4ovM15Ri6gOdOrMZYtZ6bRR4VmXWg/b72TYkM4Vh 7fxm7tpRgrizJF5O16hEsilozsTafhEyxYL3QzrOqal+v6OEdEptr6QKWQpEBuvzYOyG zVKDC6zLs5ZNrHcNxbrGCcitwk1psBU+g/GHWugVhcy6PXXDLOe3D2i571QsCU82jht6 Zq9AK1UPZHjFCaYXV8JIHiKCSg6vK7pRi2sRD/k4a2Ult07RzuQa11rrWEatFsFHUSrg HtWQ== X-Gm-Message-State: AFqh2kpD5Qnk6oBN5A76nxbA9g5vFKivNlUsdj/h22IwpejXfBtdGZjA 5nBCLhYmagsMDv9IA2NuW1qsFtMz30uLgZBIdAJ7JhbeyWRldYtxXTYQd7PzQatCm1/Ew7ojoYD +2TFFYb5imWNhZ0AvSXRliPXeZU5n+sQ= X-Received: by 2002:a05:6808:b2f:b0:363:a978:6d41 with SMTP id t15-20020a0568080b2f00b00363a9786d41mr2748382oij.280.1675064988026; Sun, 29 Jan 2023 23:49:48 -0800 (PST) X-Google-Smtp-Source: AMrXdXtwLN9AEoWvWv9UlLUlogP/JP3nP4iJPxMxZ0bIHQe3R38sRKs/Y0xOEIxoNsSg32AvKFBeycFcYEtV+vSdAGY= X-Received: by 2002:a05:6808:b2f:b0:363:a978:6d41 with SMTP id t15-20020a0568080b2f00b00363a9786d41mr2748379oij.280.1675064987727; Sun, 29 Jan 2023 23:49:47 -0800 (PST) MIME-Version: 1.0 References: <20230129025150.119972-1-xuanzhuo@linux.alibaba.com> <20230129025150.119972-3-xuanzhuo@linux.alibaba.com> <20230129021402-mutt-send-email-mst@kernel.org> <1674977308.9335406-2-xuanzhuo@linux.alibaba.com> <20230129025950-mutt-send-email-mst@kernel.org> <1674980588.489446-5-xuanzhuo@linux.alibaba.com> <20230129065705-mutt-send-email-mst@kernel.org> <1674993822.7782302-1-xuanzhuo@linux.alibaba.com> <20230129071154-mutt-send-email-mst@kernel.org> <1675044912.9269125-1-xuanzhuo@linux.alibaba.com> <20230130003158-mutt-send-email-mst@kernel.org> In-Reply-To: <20230130003158-mutt-send-email-mst@kernel.org> From: Jason Wang Date: Mon, 30 Jan 2023 15:49:36 +0800 Message-ID: Subject: Re: [PATCH v1 2/2] virtio-net: virtio_net_flush_tx() check for per-queue reset To: "Michael S. Tsirkin" Cc: Xuan Zhuo , qemu-devel@nongnu.org, Alexander Bulekov Content-Type: text/plain; charset="UTF-8" Received-SPF: pass client-ip=170.10.133.124; envelope-from=jasowang@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Mon, Jan 30, 2023 at 1:32 PM Michael S. Tsirkin wrote: > > On Mon, Jan 30, 2023 at 10:15:12AM +0800, Xuan Zhuo wrote: > > On Sun, 29 Jan 2023 07:15:47 -0500, "Michael S. Tsirkin" wrote: > > > On Sun, Jan 29, 2023 at 08:03:42PM +0800, Xuan Zhuo wrote: > > > > On Sun, 29 Jan 2023 06:57:29 -0500, "Michael S. Tsirkin" wrote: > > > > > On Sun, Jan 29, 2023 at 04:23:08PM +0800, Xuan Zhuo wrote: > > > > > > On Sun, 29 Jan 2023 03:12:12 -0500, "Michael S. Tsirkin" wrote: > > > > > > > On Sun, Jan 29, 2023 at 03:28:28PM +0800, Xuan Zhuo wrote: > > > > > > > > On Sun, 29 Jan 2023 02:25:43 -0500, "Michael S. Tsirkin" wrote: > > > > > > > > > On Sun, Jan 29, 2023 at 10:51:50AM +0800, Xuan Zhuo wrote: > > > > > > > > > > Check whether it is per-queue reset state in virtio_net_flush_tx(). > > > > > > > > > > > > > > > > > > > > Before per-queue reset, we need to recover async tx resources. At this > > > > > > > > > > time, virtio_net_flush_tx() is called, but we should not try to send > > > > > > > > > > new packets, so virtio_net_flush_tx() should check the current > > > > > > > > > > per-queue reset state. > > > > > > > > > > > > > > > > > > > > > > > > > > > What does "at this time" mean here? > > > > > > > > > Do you in fact mean it's called from flush_or_purge_queued_packets? > > > > > > > > > > > > > > > > Yes > > > > > > > > > > > > > > > > virtio_queue_reset > > > > > > > > k->queue_reset > > > > > > > > virtio_net_queue_reset > > > > > > > > flush_or_purge_queued_packets > > > > > > > > qemu_flush_or_purge_queued_packets > > > > > > > > ..... > > > > > > > > (callback) virtio_net_tx_complete > > > > > > > > virtio_net_flush_tx <-- here send new packet. We need stop it. > > > > > > > > > > > > > > > > > > > > > > > > Because it is inside the callback, I can't pass information through the stack. I > > > > > > > > originally thought it was a general situation, so I wanted to put it in > > > > > > > > struct VirtQueue. > > > > > > > > > > > > > > > > If it is not very suitable, it may be better to put it in VirtIONetQueue. > > > > > > > > > > > > > > > > Thanks. > > > > > > > > > > > > > > Hmm maybe. Another idea: isn't virtio_net_tx_complete called > > > > > > > with length 0 here? Are there other cases where length is 0? > > > > > > > > > > > > > > > > > > > > > > > What does the call stack look like? > > > > > > > > > > > > > > > > > > If yes introducing a vq state just so virtio_net_flush_tx > > > > > > > > > knows we are in the process of reset would be a bad idea. > > > > > > > > > We want something much more local, ideally on stack even ... > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Fixes: 7dc6be52 ("virtio-net: support queue reset") > > > > > > > > > > Fixes: https://gitlab.com/qemu-project/qemu/-/issues/1451 > > > > > > > > > > Reported-by: Alexander Bulekov > > > > > > > > > > Signed-off-by: Xuan Zhuo > > > > > > > > > > --- > > > > > > > > > > hw/net/virtio-net.c | 3 ++- > > > > > > > > > > 1 file changed, 2 insertions(+), 1 deletion(-) > > > > > > > > > > > > > > > > > > > > diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c > > > > > > > > > > index 3ae909041a..fba6451a50 100644 > > > > > > > > > > --- a/hw/net/virtio-net.c > > > > > > > > > > +++ b/hw/net/virtio-net.c > > > > > > > > > > @@ -2627,7 +2627,8 @@ static int32_t virtio_net_flush_tx(VirtIONetQueue *q) > > > > > > > > > > VirtQueueElement *elem; > > > > > > > > > > int32_t num_packets = 0; > > > > > > > > > > int queue_index = vq2q(virtio_get_queue_index(q->tx_vq)); > > > > > > > > > > - if (!(vdev->status & VIRTIO_CONFIG_S_DRIVER_OK)) { > > > > > > > > > > + if (!(vdev->status & VIRTIO_CONFIG_S_DRIVER_OK) || > > > > > > > > > > + virtio_queue_reset_state(q->tx_vq)) { > > > > > > > > > > > > > > btw this sounds like you are asking it to reset some state. > > > > > > > > > > > > > > > > > return num_packets; > > > > > > > > > > > > > > and then > > > > > > > > > > > > > > ret = virtio_net_flush_tx(q); > > > > > > > if (ret >= n->tx_burst) > > > > > > > > > > > > > > > > > > > > > will reschedule automatically won't it? > > > > > > > > > > > > > > also why check in virtio_net_flush_tx and not virtio_net_tx_complete? > > > > > > > > > > > > virtio_net_flush_tx may been called by timer. We stop timer/bh during device reset, do we need to do the same with vq reset? > > > > > > > > > > > > Thanks. > > > > > > > > > > timer won't run while flush_or_purge_queued_packets is in progress. > > > > > > > > Is timer not executed during the VMEXIT process? Otherwise, we still have to > > > > consider that after the flush_or_purge_queued_packets, this process before the > > > > structure is cleared. > > > > > > > > > > > > void virtio_queue_reset(VirtIODevice *vdev, uint32_t queue_index) > > > { > > > VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev); > > > > > > if (k->queue_reset) { > > > k->queue_reset(vdev, queue_index); > > > } > > > > > > __virtio_queue_reset(vdev, queue_index); > > > } > > > > > > > > > No timers do not run between k->queue_reset and __virtio_queue_reset. > > > > > > > > > > Even if it can be processed in virtio_net_tx_complete, is there any good way? > > > > This is a callback, it is not convenient to pass the parameters. > > > > > > > > Thanks > > > > > > > > > How about checking that length is 0? > > > > > > I think that check length is not a good way. This modifys the semantics of 0. 0 seems to mean "purge" and > It is > > not friendly to the future maintenance. On the other hand, qemu_net_queue_purge() > > will pass 0, and this function is called by many places. That's exactly what we want actually, when do purge we don't need a flush? > > > > How about we add an api in queue.c to replace the sent_cb callback on queue? > > > > Thanks. > > OK I guess. Jason? Not sure, anything different from adding a check in virtio_net_tx_complete()? (assuming bh and timer is cancelled or deleted). Thanks > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > } > > > > > > > > > > > > > > > > > > > > -- > > > > > > > > > > 2.32.0.3.g01195cf9f > > > > > > > > > > > > > > > > > > > > > > > > >